A ray of light from a denser medium strikes a rarer medium at an angle incidence as shown in figure. The reflected and refracted rays make an angle of 90 with each other. The angles of reflection and refraction and r and r1. The critical angle is

Question

Philoid · Accepted Answer

According to Snell’s law

But i+r=90° (Reflected and refracted rays are at an angle of 900).

⇒

⇒ μ =.

⇒ μ =

⇒

Critical angle = μ =

⇒

⇒ sin i_c = tan r

⇒ i_c = sin^-1 (Tan r)

Therefore, the critical angle i_c = sin^-1(tan r)

hence the option A is correct.